For a notebook computer powered by a power adapter, the power adapter may output a single voltage to a voltage conversion unit of the notebook computer. The voltage conversion unit may convert the single voltage into different voltages, such as 3V3, 5V_SYS, 5V_STBY, 12V_SYS voltages, and a power-good signal, and outputs the different voltages and the power-good signal to a motherboard of the notebook computer. However, if time sequences of the different voltages and the power-good signal output from the voltage conversion unit do not satisfy a time sequence required by the motherboard, the notebook computer may not be able to operate.